fs/erofs/decompressor_deflate.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 #include <linux/zlib.h>
   3 #include "compress.h"
   4
   5 struct z_erofs_deflate {
   6         struct z_erofs_deflate *next;
   7         struct z_stream_s z;
   8         u8 bounce[PAGE_SIZE];
   9 };
  10
  11 static DEFINE_SPINLOCK(z_erofs_deflate_lock);
  12 static unsigned int z_erofs_deflate_nstrms, z_erofs_deflate_avail_strms;
  13 static struct z_erofs_deflate *z_erofs_deflate_head;
  14 static DECLARE_WAIT_QUEUE_HEAD(z_erofs_deflate_wq);
  15
  16 module_param_named(deflate_streams, z_erofs_deflate_nstrms, uint, 0444);
  17
  18 void z_erofs_deflate_exit(void)
  19 {
  20         /* there should be no running fs instance */
  21         while (z_erofs_deflate_avail_strms) {
  22                 struct z_erofs_deflate *strm;
  23
  24                 spin_lock(&z_erofs_deflate_lock);
  25                 strm = z_erofs_deflate_head;
  26                 if (!strm) {
  27                         spin_unlock(&z_erofs_deflate_lock);
  28                         continue;
  29                 }
  30                 z_erofs_deflate_head = NULL;
  31                 spin_unlock(&z_erofs_deflate_lock);
  32
  33                 while (strm) {
  34                         struct z_erofs_deflate *n = strm->next;
  35
  36                         vfree(strm->z.workspace);
  37                         kfree(strm);
  38                         --z_erofs_deflate_avail_strms;
  39                         strm = n;
  40                 }
  41         }
  42 }
  43
  44 int __init z_erofs_deflate_init(void)
  45 {
  46         /* by default, use # of possible CPUs instead */
  47         if (!z_erofs_deflate_nstrms)
  48                 z_erofs_deflate_nstrms = num_possible_cpus();
  49
  50         for (; z_erofs_deflate_avail_strms < z_erofs_deflate_nstrms;
  51              ++z_erofs_deflate_avail_strms) {
  52                 struct z_erofs_deflate *strm;
  53
  54                 strm = kzalloc(sizeof(*strm), GFP_KERNEL);
  55                 if (!strm)
  56                         goto out_failed;
  57
  58                 /* XXX: in-kernel zlib cannot shrink windowbits currently */
  59                 strm->z.workspace = vmalloc(zlib_inflate_workspacesize());
  60                 if (!strm->z.workspace) {
  61                         kfree(strm);
  62                         goto out_failed;
  63                 }
  64
  65                 spin_lock(&z_erofs_deflate_lock);
  66                 strm->next = z_erofs_deflate_head;
  67                 z_erofs_deflate_head = strm;
  68                 spin_unlock(&z_erofs_deflate_lock);
  69         }
  70         return 0;
  71
  72 out_failed:
  73         pr_err("failed to allocate zlib workspace\n");
  74         z_erofs_deflate_exit();
  75         return -ENOMEM;
  76 }
  77
  78 int z_erofs_load_deflate_config(struct super_block *sb,
  79                         struct erofs_super_block *dsb, void *data, int size)
  80 {
  81         struct z_erofs_deflate_cfgs *dfl = data;
  82
  83         if (!dfl || size < sizeof(struct z_erofs_deflate_cfgs)) {
  84                 erofs_err(sb, "invalid deflate cfgs, size=%u", size);
  85                 return -EINVAL;
  86         }
  87
  88         if (dfl->windowbits > MAX_WBITS) {
  89                 erofs_err(sb, "unsupported windowbits %u", dfl->windowbits);
  90                 return -EOPNOTSUPP;
  91         }
  92
  93         erofs_info(sb, "EXPERIMENTAL DEFLATE feature in use. Use at your own risk!");
  94         return 0;
  95 }
  96
  97 int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
  98                                struct page **pagepool)
  99 {
 100         const unsigned int nrpages_out =
 101                 PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
 102         const unsigned int nrpages_in =
 103                 PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
 104         struct super_block *sb = rq->sb;
 105         unsigned int insz, outsz, pofs;
 106         struct z_erofs_deflate *strm;
 107         u8 *kin, *kout = NULL;
 108         bool bounced = false;
 109         int no = -1, ni = 0, j = 0, zerr, err;
 110
 111         /* 1. get the exact DEFLATE compressed size */
 112         kin = kmap_local_page(*rq->in);
 113         err = z_erofs_fixup_insize(rq, kin + rq->pageofs_in,
 114                         min_t(unsigned int, rq->inputsize,
 115                               sb->s_blocksize - rq->pageofs_in));
 116         if (err) {
 117                 kunmap_local(kin);
 118                 return err;
 119         }
 120
 121         /* 2. get an available DEFLATE context */
 122 again:
 123         spin_lock(&z_erofs_deflate_lock);
 124         strm = z_erofs_deflate_head;
 125         if (!strm) {
 126                 spin_unlock(&z_erofs_deflate_lock);
 127                 wait_event(z_erofs_deflate_wq, READ_ONCE(z_erofs_deflate_head));
 128                 goto again;
 129         }
 130         z_erofs_deflate_head = strm->next;
 131         spin_unlock(&z_erofs_deflate_lock);
 132
 133         /* 3. multi-call decompress */
 134         insz = rq->inputsize;
 135         outsz = rq->outputsize;
 136         zerr = zlib_inflateInit2(&strm->z, -MAX_WBITS);
 137         if (zerr != Z_OK) {
 138                 err = -EIO;
 139                 goto failed_zinit;
 140         }
 141
 142         pofs = rq->pageofs_out;
 143         strm->z.avail_in = min_t(u32, insz, PAGE_SIZE - rq->pageofs_in);
 144         insz -= strm->z.avail_in;
 145         strm->z.next_in = kin + rq->pageofs_in;
 146         strm->z.avail_out = 0;
 147
 148         while (1) {
 149                 if (!strm->z.avail_out) {
 150                         if (++no >= nrpages_out || !outsz) {
 151                                 erofs_err(sb, "insufficient space for decompressed data");
 152                                 err = -EFSCORRUPTED;
 153                                 break;
 154                         }
 155
 156                         if (kout)
 157                                 kunmap_local(kout);
 158                         strm->z.avail_out = min_t(u32, outsz, PAGE_SIZE - pofs);
 159                         outsz -= strm->z.avail_out;
 160                         if (!rq->out[no]) {
 161                                 rq->out[no] = erofs_allocpage(pagepool,
 162                                                 GFP_KERNEL | __GFP_NOFAIL);
 163                                 set_page_private(rq->out[no],
 164                                                  Z_EROFS_SHORTLIVED_PAGE);
 165                         }
 166                         kout = kmap_local_page(rq->out[no]);
 167                         strm->z.next_out = kout + pofs;
 168                         pofs = 0;
 169                 }
 170
 171                 if (!strm->z.avail_in && insz) {
 172                         if (++ni >= nrpages_in) {
 173                                 erofs_err(sb, "invalid compressed data");
 174                                 err = -EFSCORRUPTED;
 175                                 break;
 176                         }
 177
 178                         if (kout) { /* unlike kmap(), take care of the orders */
 179                                 j = strm->z.next_out - kout;
 180                                 kunmap_local(kout);
 181                         }
 182                         kunmap_local(kin);
 183                         strm->z.avail_in = min_t(u32, insz, PAGE_SIZE);
 184                         insz -= strm->z.avail_in;
 185                         kin = kmap_local_page(rq->in[ni]);
 186                         strm->z.next_in = kin;
 187                         bounced = false;
 188                         if (kout) {
 189                                 kout = kmap_local_page(rq->out[no]);
 190                                 strm->z.next_out = kout + j;
 191                         }
 192                 }
 193
 194                 /*
 195                  * Handle overlapping: Use bounced buffer if the compressed
 196                  * data is under processing; Or use short-lived pages from the
 197                  * on-stack pagepool where pages share among the same request
 198                  * and not _all_ inplace I/O pages are needed to be doubled.
 199                  */
 200                 if (!bounced && rq->out[no] == rq->in[ni]) {
 201                         memcpy(strm->bounce, strm->z.next_in, strm->z.avail_in);
 202                         strm->z.next_in = strm->bounce;
 203                         bounced = true;
 204                 }
 205
 206                 for (j = ni + 1; j < nrpages_in; ++j) {
 207                         struct page *tmppage;
 208
 209                         if (rq->out[no] != rq->in[j])
 210                                 continue;
 211
 212                         DBG_BUGON(erofs_page_is_managed(EROFS_SB(sb),
 213                                                         rq->in[j]));
 214                         tmppage = erofs_allocpage(pagepool,
 215                                                   GFP_KERNEL | __GFP_NOFAIL);
 216                         set_page_private(tmppage, Z_EROFS_SHORTLIVED_PAGE);
 217                         copy_highpage(tmppage, rq->in[j]);
 218                         rq->in[j] = tmppage;
 219                 }
 220
 221                 zerr = zlib_inflate(&strm->z, Z_SYNC_FLUSH);
 222                 if (zerr != Z_OK || !(outsz + strm->z.avail_out)) {
 223                         if (zerr == Z_OK && rq->partial_decoding)
 224                                 break;
 225                         if (zerr == Z_STREAM_END && !outsz)
 226                                 break;
 227                         erofs_err(sb, "failed to decompress %d in[%u] out[%u]",
 228                                   zerr, rq->inputsize, rq->outputsize);
 229                         err = -EFSCORRUPTED;
 230                         break;
 231                 }
 232         }
 233
 234         if (zlib_inflateEnd(&strm->z) != Z_OK && !err)
 235                 err = -EIO;
 236         if (kout)
 237                 kunmap_local(kout);
 238 failed_zinit:
 239         kunmap_local(kin);
 240         /* 4. push back DEFLATE stream context to the global list */
 241         spin_lock(&z_erofs_deflate_lock);
 242         strm->next = z_erofs_deflate_head;
 243         z_erofs_deflate_head = strm;
 244         spin_unlock(&z_erofs_deflate_lock);
 245         wake_up(&z_erofs_deflate_wq);
 246         return err;
 247 }